Dichanthelium portoricense grows in sandy woods, low pinelands, savannahs,
and coastal sand dunes, usually in moist places. Its range extends south from
the Flora region into Mexico, the Caribbean, and Mesoamerica. It is a
highly variable species with numerous intergrading forms, some possibly resulting
from hybridization with other widespread species in the same region, such as
D. sphaerocarpon and D.
commutatum.

Plants densely cespitose. Culms seldom over50 cm, slender, suberect,
ascending or spreading; nodes more or less densely pubescent; fall
phase branching extensively from the lower and midculm nodes, with conspicuous,
flabellate fascicles of branches and reduced blades. Cauline sheaths
shorter than the internodes, lower sheaths usually pilose with papillose-based
hairs, upper sheaths often short-pubescent; midculm sheaths about 1/2
as long as the internodes; blades usually 2-6 mm wide, more than 8 times
longer than wide, relatively firm, erect to ascending, often yellowish-green,
abaxial surfaces densely pubescent with short papillose-based hairs or short-pubescent
with subappressed hairs, adaxial surfaces more or less densely pilose, hairs
to 6 mm, conspicuous, erect or ascending, occasionally with shorter hairs underneath.
Spikelets 1.3-1.6 mm, usually broadly obovoid.

Dichanthelium acuminatum subsp. implicatum usually grows
in low, moist areas, including open woodlands, meadows, bogs, and cedar
and hemlock swamps, and also in drier, sandy areas. Its range extends
from south central Canada to the midwestern and northeastern United
States. It intergrades occasionally with the more widespread subsp. fasciculatum.

Dichanthelium portoricense subsp. patulum is more common in moist,
sandy pinelands and savannahs than subsp. portoricense. It also grows
in coastal sand dunes, but is less abundant there than subsp. portoricense.
It is the more variable of the two subspecies, grading into subsp. portoricense
as well as D. commutatum. More robust plants
are recognized by some as Panicum patentifolium Nash. Occasional specimens,
recognized by some as P. webberianum Nash, resemble the widespread D. sphaerocarpon.

Dichanthelium portoricense subsp. portoricense is more common
than subsp. patulum in coastal sand dunes.
It also grows in sandy pinelands and savannahs. It resembles D.
aciculare somewhat, but that species usually has ascending-pilose culms,
strongly involute or acicular blades, and longer spikelets.

Habitat and ecology: Common in a wide variety of habitats, including woodlands, moist prairies, and along railroads and lakes.

Occurence in the Chicago region: native

Etymology: Dichanthelium comes from the Greek words di, meaning twice, and anth, meaning flowering, referring to plants that may have two flowering periods. Acuminatum means "tapering to a long point." Implicatum means tangled.

[Deam splits Dichanthelium acuminatum subsp. implicatum into three taxa in the genus Panicum.] [Panicum albemarlense:] I have only one specimen of this grass from Indiana and it is in the autumnal phase. I am not able to make a satisfactory study of this species from the few specimens at hand. Some authors refer it to a form of Panicum meridionale, to which it may belong. It is found in sandy soils. [Panicum implicatum:] Local to infrequent but common in its habitat. It is generally found in moist, sandy soil on the marly borders of lakes, in interdunal flats, and rarely in dry, sandy soil. I think this grass is restricted to the lake area and that all reports of it from south of this area should be referred to some other species, most probably to Panicurn huachucae. This Panicum is difficult to separate from Panicum huachucae, but usually the length of the spikelet and the color of the whole plant are sufficient to distinguish them. [Panicum meridionale:] Infrequent in the lake area, probably rather local. It is found in moist soil on the borders of marshes, in interdunal flats, and on the bases of wooded slopes where there are open spaces not sodded over with grasses and sedges. This plant usually can be distinguished easily from the preceding and the following species by the puberulence in the channels between the nerves of the sheaths and sometimes of the culms, and the puberulent panicle.